NZ heat-pump cost + seasonal COP — ASHP & GSHP (compiled synthesis)
Compiled research — upstream-referenced
A Perplexity Deep Research synthesis. ASHP cost/COP is well-supported by current NZ primary sources (EECA, BRANZ, installers) — HIGH confidence. GSHP figures rest on thin NZ data (East Harbour 2013 escalated to 2025; EECA Bay of Plenty 2024 indicative case studies with 30% contingency) — MEDIUM confidence, ±30%. Tag model cells accordingly (ASHP sourced; GSHP sourced-but-medium).
Summary
A quantitative NZ reference for air-source (ASHP) and ground-source (GSHP) heat pumps: installed cost in NZD per kW thermal and realistic seasonal COP (SCOP) for space heating, residential and community scale. ASHP installs at roughly 500–1,100/kW_th with an NZ-average SCOP near 3.5 (≈2.0 in the coldest regions, >4.0 in the warmest). GSHP costs more (1,700–3,500/kW_th residential, 1,000–2,700 community) but delivers a higher and more seasonally stable SCOP (~3.5–5.0) because ground/groundwater sits at 12–16°C year-round. It fills the NI model's heat-pump cost cells and the heat↔electricity COP coupling (`@cop_air`, `@cop_gshp`), and feeds D01. *(This synthesis covers **space-heating** heat pumps; for the **hot-water (DHW)** duty, a CO₂ heat-pump water heater performs at 36–46% of resistance grid electricity / effective COP ~2.5 per the recent BRANZ field study [[ot_038_branz-sr488-water-heating-performance|OT_038]].)* *(The GSHP cost + COP figures now have their NZ primary ingested — [[ot_086_gns-bop-reta-geothermal-assessment-2024|OT_086]] (GNS/EECA BoP RETA, SR 2024/02): Whakatāne Hospital 5.61M ≈ 2,670/kW_th, Growers 6.57M ≈ $1,370/kW_th, COP 2.77 @ 15 °C rising to 4.0 @ 30 °C (Tables 5.1–5.3). Indicative/30%-contingency, open-loop-aquifer → stays medium. Note SR 2024/02’s exec summary reverses the two site totals vs its own tables; the tables govern.)*
Key claims
- claim: "NZ air-source heat pump (ASHP) installed cost is roughly $500–1,100/kW thermal for residential high-wall splits and $700–1,300/kW_th for ducted/community multi-zone; hardware-only ~$300–900/kW_th. A typical 2.5–5 kW split totals $2,000–$4,500 installed."
source_location: "§1 Summary / §3.3 Total Installed Costs"
- claim: "NZ average ASHP seasonal COP is ~3.5 (EECA Electric Homes Technical Report 2024), dropping to ~2.0 in very cold regions and exceeding 4.0 in warm regions; BRANZ Level notes nameplate COP 2.0–4.5 degrades to ~1.5–3.0 in the field."
source_location: "§4.2 NZ ASHP Seasonal COP Data / §1"
- claim: "ASHP design SCOP by NZ climate: Auckland/Northland 3.0–4.0; Wellington/Waikato/BoP 2.8–3.5; Nelson/Marlborough 2.8–3.3; Christchurch/Dunedin 2.3–3.0; Central Otago/Southland 2.0–2.8 (low-temp ~20°C air delivery; hydronic at 45–55°C cuts COP 15–25%)."
source_location: "§4.5 Practical NZ ASHP SCOP Summary"
- claim: "NZ ground-source heat pump (GSHP) installed cost is ~$1,700–2,800/kW_th (horizontal loop) or $2,250–3,500/kW_th (vertical bore) residential, and ~$1,000–2,700/kW_th community/commercial (excludes distribution); residential systems total $17,000–$40,000 in 2025 NZD."
source_location: "§5.4 NZ GSHP Cost Summary"
- claim: "NZ GSHP seasonal COP is ~3.5–5.0 (heating-only, 40–45°C delivery) and far more seasonally stable than ASHP (<10% variation), because ground/groundwater is 12–16°C year-round; measured Queenstown horizontal-loop SCOP 4.8."
source_location: "§6.4 NZ GSHP SCOP Summary / §1"
- claim: "Whakatāne Hospital GSHP (EECA Bay of Plenty RETA 2024): 2.1 MW_th heating, ~$2,670/kW_th installed (incl. 30% contingency), COP 2.77 at a 15°C source, >40% annual energy reduction and >35% peak-electrical reduction vs ASHP."
source_location: "§5.2 / §7.2 Whakatāne Hospital"
- claim: "NZGA sizing rule: a GSHP sized to 60% of peak heating load can supply ~97% of annual heating demand — the recommended base-load strategy for community-scale GSHP in NZ."
source_location: "§10.5 Key Assumptions (point 4)"Neobiome Intelligence relevance
Fills the heat-pump cost cells (④) and the COP coupling (④b). Recommended model values:
| Cell | Value | Tag | Basis |
|---|---|---|---|
heat_pump_air cost | ~800/kW_th installed (range 500–1,100) | sourced | NZ installer pricing + EECA |
@cop_air (national) | 3.5; pilot (Nelson/Tasman) ~3.0 | sourced | EECA Electric Homes 2024 (NZ avg 3.5); §4.5 regional |
heat_pump_ground cost | ~2,000/kW_th residential, ~1,500 community | sourced (medium) | East Harbour 2013 escalated + EECA RETA 2024 |
@cop_gshp | 4.0–4.5 (heating-only, 40–45°C) | sourced (medium) | East Harbour / Stiebel-NZGA / EECA RETA |
Heat↔electricity coupling. The model already carries heat_pump consumes electricity = heat ÷ COP. With pilot SCOP ~3.0, every 1 kWh of electricity delivers ~3 kWh of space heat — so electrifying the pilot’s space-heat demand adds roughly one-third of that demand back as electricity load (the cross-domain term the engine sizes generation against).
GSHP is a strong but capital-heavy, site-gated option. Higher, more stable SCOP and lower running cost, but ~2–3× the ASHP capex, 200–450 m² of ground (horizontal) or drilling + RMA/well consent (vertical), and a thin NZ installer market. The NZGA “size to 60% of peak → 97% of annual” rule is a useful base-load sizing default if GSHP enters the portfolio.
Caveat for calculation use. ASHP figures are robust; GSHP figures are MEDIUM (±30%) — several derive from 2013 data escalated to 2025 or from indicative EECA case studies carrying 30% contingency. NZ has no metered heat-pump SCOP fleet dataset, so all SCOPs are EECA/modelled estimates, not field-metered. Treat GSHP cells as sourced-but-provisional pending the EECA Bay of Plenty RETA primary (RT_203) and a real installer quote.
Research targets
Documents to retrieve
- EECA Bay of Plenty Regional Energy Transition Accelerator — Geothermal Assessment (2024, GNS SR2024/02) — the key NZ GSHP cost+COP primary behind the Whakatāne Hospital (~
2,670/kW_th, COP 2.77) and Growers (~1,370/kW_th) figures (eeca.govt.nz PDF). New target RT_203; firms the GSHP cells from medium → sourced. - EECA Electric Homes Technical Report (March 2024) — primary for the ASHP NZ-average SCOP 3.5 (and 2.0 cold / 4.0+ warm). Already tracked as RT_096. No new target.
- East Harbour Energy (2013) Low-Enthalpy Geothermal Technological Economics Review — the only published NZ per-kW GSHP cost breakdown; dated (2013 NZD, escalated here). Lower priority; cross-ref RT_203.
Research gaps
- No NZ metered heat-pump SCOP dataset (no equivalent of UK Heat Pump Monitoring / European SEPEMO) — all NZ SCOPs are EECA estimates/modelled, not field-metered fleet data. Not closable by document retrieval; flagged for honesty.
- GSHP installer quote for a community-scale NZ system (akin to RT_089 for BESS) would replace the ±30% escalated estimate with a real number.
Connections
Links to
Referenced by
Sources (6): CR_015 · OT_029 · OT_038 · OT_041 · OT_086 · OT_162
EDT domains (2): D01: Renewable Energy & Storage Systems · D04: Sustainable Habitat & Building Technology